Egyptians on a motorbike pass by burnt poster of Egypt's ousted President Mohammed Morsi in Nahda Square, near Cairo University in Giza, in Cairo, Egypt, on Thursday. / Amr Nabil, AP

by Sarah Lynch, Special for USA TODAY

by Sarah Lynch, Special for USA TODAY

CAIRO - Angry supporters of ousted president Mohammed Morsi staged protests and burned buildings Thursday as President Obama condemned the violence on both sides and canceled next month's joint military operations.

The unrest came a day after at least 638 people were killed in violence nationwide, including 43 police officers, the Health Ministry said. Most of the deaths occurred when security forces smashed two pro-Morsi sit-in camps in the capital. In the Nasr City district, 288 people were killed.

The Health Ministry said 3,994 people were injured.

After the police moved on the camps, street battles broke out across Egypt. Government buildings and police stations were attacked, roads were blocked, and Christian churches were torched, Interior Minister Mohammed Ibrahim said.

The Egyptian government on Thursday defended its actions of the previous day.

"The security agencies were keen to adopt a gradual plan to avoid bloodshed and falling of victims," a State Information Service statement said. It said authorities appealed to people to leave, provided a safe exit, then used tear gas to disperse the crowd.

"Meanwhile, those who were in the two sit-ins started shooting at the police forces," the statement said.

On Thursday, angry protesters set fire to a two-story villa and a four-story administrative building housing the local government in the neighboring city of Giza, home to the country's iconic pyramids and site of one of the encampments.

The Interior Ministry, which is in charge of national security, countered by authorizing police to use deadly force to protect themselves and state institutions. The government also pledged to confront "terrorist actions and sabotage" it blamed on Morsi's Muslim Brotherhood.

The brotherhood called for a nationwide "Millions March of Anger" on Friday.

Outside the Al-Iman mosque near the other encampment, robust chants against the military and police erupted following midafternoon prayers Thursday. Parts of the pavement were torched and several burned-out vehicles sat neglected on roads leading to the area, now bearing little sign of the labyrinth of tents that crammed the space days earlier.

People came to show solidarity with those waiting for the dead to be carried from the mosque. They waved posters of Morsi as bodies and coffins weaved through the crowd.

"We will not stop at this death," said Motaz Ismail, 41, a manager at a chemical trading company. "It just increases encouragement to continue the way of the revolution, democracy until we get our country back."

Mourners, doctors, onlookers and volunteers crowded around the Al-Iman mosque, where bodies had been taken. Coffins, one by one, were removed to be taken for burial. Victims' names were scribbled on white sheets covering their bodies, some of which were charred. Posters of Morsi were scattered on the floor.

Outside the mosque, men wiped tears from their eyes. Some read the Quran.

"We're waiting for the bodies to be buried, and tomorrow maybe there will be another revolution," said Ahmad Abou Anain, 31, as he handed out sandwiches in the crowd. "I will ask God to kill Sisi," referring to Egyptian military chief Abdel Fattah al-Sisi.

Others, however, remained steadfast in their commitment to the military, underscoring the nation's deep divisions.

"I love the military," said Mohammed al-Sayyed, a taxi driver. "Morsi, the Muslim Brotherhood, do not represent the country. He was only committed to religion and prayer. But he didn't work on politics."

That was why so many people supported al-Sisi when he took charge of the country July 3, al-Sayyed said.

"It was only because they didn't want Morsi," he said.

Banks and the stock exchange were closed Thursday and museums and archaeological sites are sealed indefinitely, the government said. Much of the nation is living under a one-month state of emergency with overnight curfews. The U.S. Embassy in Cairo was shut to the public, and consular services were suspended.

The State Department warned Thursday against traveling to Egypt and urged Americans living there to leave.

Obama condemned the violence and said the Egyptian interim government needed to lift the state of emergency and move toward democratic elections. He said he wanted to continue the long-standing U.S. relationship with Egypt, but said he told the Egyptian military he was canceling joint military operations scheduled for next month.

"America cannot determine the future of Egypt. ... We don't take sides with any particular party or political figure," Obama said Thursday. "That's a task for the Egyptian people. We want a peaceful, democratic, prosperous Egypt, that's our interest. We recognize that change takes time."

Earlier this month, al-Sisi criticized the United States for refusing to endorse his ouster of Morsi, whose Islamist policies and refusal to abide by court rulings prompted protests by millions of Egyptians in June. Al-Sisi told The Washington Post that the Obama administration "turned (its) back on the Egyptians, and they won't forget that."

Meanwhile, the interim government is coming unhinged.

Sources told Ahram Online, a local news publication, that Deputy Prime Ministers Ziad Bahaa El-Din and Hossam Eissa will submit their resignations. On Wednesday, interim Vice President Mohamed ElBaradei resigned, saying he disagreed with the assaults.

Tamarod, the youth group behind the mass anti-Morsi protests that preceded the coup, said ElBaradei was dodging his responsibility at a time when his services were needed.

After weeks of political stalemate between the military-backed interim government and Morsi's Muslim Brotherhood and its Islamist allies, the violence may have crushed any prospects of mediation.

"There was a slight glimmer of hope for some mediation process or negotiation before yesterday's events," said Shadi Hamid, director of research for the Brookings Doha Center. "All of that is pretty much moot at this point."

The only real option for Morsi supporters is to stage more protests to put pressure on the government, Hamid said. If the Brotherhood stops protesting, repression would continue and the military would move to dismantle the organization, he said.

Since the coup, Brotherhood leaders have been arrested and their assets frozen. The Interior Ministry, which supervises the police, said 200 protesters, many from the Muslim Brotherhood, are under arrest for the protests.

A mass police funeral - with caskets draped in the white-red-and-black Egyptian flag - was held in Cairo for some of the 43 security troops killed in Wednesday's clashes.

Interior Minister Mohammed Ibrahim led the mourners. A police band played funerary music as a somber funeral procession moved with the coffins placed atop red fire engines.

Cairo, a city of 18 million people, was uncharacteristically quiet Thursday, with only a fraction of its usually hectic traffic and many stores and government offices shuttered. Many people hunkered down at home for fear of more violence.

The latest events in Egypt drew widespread condemnation from the Muslim world and the West, including the United States, Egypt's main foreign backer for over 30 years.

Interim Prime Minister Hazem el-Beblawi said in a televised address Wednesday to the nation that it was a "difficult day" and that he regretted the bloodshed.

Morsi has been under house arrest at an undisclosed location. Other Brotherhood leaders have been charged with inciting violence or conspiring in the killing of protesters.